The present invention relates to a connecting device for a wiper system which comprises a wiper arm of which the front end is articulated to the superstructure of the wiper blade in its medium portion and which comprises a control arm of which the front end is articulated to said superstructure at its rear end.
Wiper systems of the thus defined type are well known in prior art, just as the fact that these systems allow the surface to be wiped by the wiper blade to be increased with respect to the wiper systems which are not provided with a control arm.
British Pat. Nos. 832,466 and 977,607 may be mentioned by way of example. However, neither these two patents nor any other patent known to the applicant show the constructive details of the articulation between the front end of the control arm and the rear end of the superstructure of the wiper blade.
On a flat windshield the articulation between the control arm and the superstructure of the wiper blade may possibly consist of a simple pivot connection. This, however is no longer true for a curved windshield. Indeed, because of the torsional forces which are transmitted to the articulation or connection by the control arm, it is indispensable that said articulation is a ball-joint type articulation.
If on a curved windshield the ball-joint type solution seems to be an adequate solution at first sight, it is however to be noted that the ball-joint connection, which is well known in some other wiper systems, has at least the following disadvantages:
it is relatively complex if it is designed for a perfect working over a sufficiently long period,
for ensuring a sufficiently long life period it is necessary to use special materials,
because of its complexity and because of the use of special materials it is relatively expensive.